[quanticle]

Testing delete code against production isn't that big of a deal. If you screw up, the "oops" is immediate and obvious, as is the recovery strategy — restore from backup.

The real fear with deploying code directly against production is data corruption. I've seen more than one instance where two pieces of code, both of which had impeccable unit test coverage, interacted in strange ways to cause data corruption, because of mistaken assumptions that their respective authors had about each others' code. This is the kind of thing that you need integration tests to catch. Integration tests need some kind of common environment (even if it is ephemeral) in which to run. And now you have a development environment.

[chadcmulligan]

lol, I didn't enumerate all the ways this is bad. Restoring from backup can mean an outage and possible loss of data (the intervening transactions that are lost), this is to be avoided, it also assumes your backups work, often an untested case. Corruption is bad to, the entire idea is bad.